methane

H220: Extremely flammable gas [Danger Flammable gases]

P203, P210, P222, P280, P377, P381, and P403 (click each P-code to see the statement)

H220 (100%): Extremely flammable gas [Danger Flammable gases]

H280 (56.4%): Contains gas under pressure; may explode if heated [Warning Gases under pressure]

H281 (20.7%): Contains refrigerated gas; may cause cryogenic burns or injury [Warning Gases under pressure]

P203, P210, P222, P280, P282, P336+P317, P377, P381, P403, and P410+P403 (click each P-code to see the statement)

Aggregated GHS information provided per 605 reports by companies from 11 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H280: Contains gas under pressure; may explode if heated [Warning Gases under pressure]

H281: Contains refrigerated gas; may cause cryogenic burns or injury [Warning Gases under pressure]

Fresh air, rest. Artificial respiration may be needed. Refer for medical attention.

ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. Refer for medical attention .

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Remove victim to open air. If he is overcome by gas, apply artificial resuscitation. (USCG, 1999)

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SKIN: CAUTION: Exposure of skin to compressed gases may result in freezing of the skin. Treatment for frostbite may be necessary. Remove the victim from the source of contamination. IMMEDIATELY wash affected areas gently with COLD water (and soap, if necessary) while removing and isolating all contaminated clothing. Dry carefully with clean, soft towels. If symptoms such as inflammation or irritation develop, IMMEDIATELY call a physician or go to a hospital for treatment.

INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. If symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop, call a physician and be prepared to transport the victim to a hospital. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing.

INGESTION: This compound is a gas, therefore inhalation is the first route of exposure. (NTP, 1992)

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

Refer to the "General First Aid" section. Specific First Aid: Clothing frozen to the skin should be thawed before being removed. In case of contact with liquefied gas, only medical personnel should attempt thawing frosted parts. In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin. (ERG, 2024)

General First Aid:

· Call 911 or emergency medical service.

· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.

· Move victim to fresh air if it can be done safely.

· Administer oxygen if breathing is difficult.

· If victim is not breathing:

-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.

-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).

-- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.

· Remove and isolate contaminated clothing and shoes.

· For minor skin contact, avoid spreading material on unaffected skin.

· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.

· For severe burns, immediate medical attention is required.

· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.

· Keep victim calm and warm.

· Keep victim under observation.

· For further assistance, contact your local Poison Control Center.

· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.

Specific First Aid:

· Clothing frozen to the skin should be thawed before being removed.

· In case of contact with liquefied gas, only medical personnel should attempt thawing frosted parts.

· In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin.

In Canada, an Emergency Response Assistance Plan (ERAP) may be required for this product. Please consult the shipping paper and/or the "ERAP" section.

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED. CAUTION: Hydrogen (UN1049), Deuterium (UN1957), Hydrogen, refrigerated liquid (UN1966) and Hydrogen and Methane mixture, compressed (UN2034) will burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.).

SMALL FIRE: Dry chemical or CO2.

LARGE FIRE: Water spray or fog. If it can be done safely, move undamaged containers away from the area around the fire. CAUTION: For LNG - Liquefied natural gas (UN1972) pool fires, DO NOT USE water. Use dry chemical or high-expansion foam.

FIRE INVOLVING TANKS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Do not direct water at source of leak or safety devices; icing may occur. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks in direct contact with flames. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2024)

Shut off supply; if not possible and no risk to surroundings, let the fire burn itself out. In other cases extinguish with water spray, powder, carbon dioxide. In case of fire: keep cylinder cool by spraying with water. Combat fire from a sheltered position.

Wear self contained breathing apparatus for fire fighting if necessary.

Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Keep unauthorized personnel away.

· Stay upwind, uphill and/or upstream.

· Many gases are heavier than air and will spread along the ground and collect in low or confined areas (sewers, basements, tanks, etc.).

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

· All equipment used when handling the product must be grounded.

· Do not touch or walk through spilled material.

· Stop leak if you can do it without risk.

· If possible, turn leaking containers so that gas escapes rather than liquid.

· Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material.

· Do not direct water at spill or source of leak.

CAUTION: For LNG - Liquefied natural gas (UN1972), DO NOT apply water, regular or alcohol-resistant foam directly on spill. Use a high-expansion foam if available to reduce vapors.

· Prevent spreading of vapors through sewers, ventilation systems and confined areas.

· Isolate area until gas has dispersed.

CAUTION: When in contact with refrigerated/cryogenic liquids, many materials become brittle and are likely to break without warning.

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

LARGE SPILL: Consider initial downwind evacuation for at least 800 meters (1/2 mile).

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. In fires involving Liquefied Petroleum Gases (LPG) (UN1075), Butane (UN1011), Butylene (UN1012), Isobutylene (UN1055), Propylene (UN1077), Isobutane (UN1969), and Propane (UN1978), also refer to the "BLEVE - Safety Precautions" section. (ERG, 2024)

Immediate precautionary measure

· Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

Large Spill

· Consider initial downwind evacuation for at least 800 meters (1/2 mile).

· If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions.

· In fires involving Liquefied Petroleum Gases (LPG) (UN1075), Butane (UN1011), Butylene (UN1012), Isobutylene (UN1055), Propylene (UN1077), Isobutane (UN1969), and Propane (UN1978), also refer to the "BLEVE - Safety Precautions" section.

Evacuate danger area! Personal protection: self-contained breathing apparatus. Consult an expert! Ventilation. Remove all ignition sources. NEVER direct water jet on liquid.

Clean up promptly by sweeping or vaccum.

Do not let product enter drains.

Evacuate danger area! Personal protection: self-contained breathing apparatus. Consult an expert! Ventilation. Remove all ignition sources. NEVER direct water jet on liquid.

By forced ventilation, maintain concn of gas below the range of explosive mixture. Remove the tank or cylinder to an open area. Leave to bleed off in the atmosphere.

Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. If possible, turn leaking containers so that gas escapes rather than liquid. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Do not direct water at spill or source of leak. CAUTION: For LNG - Liquefied natural gas (UN1972), DO NOT apply water, regular or alcohol-resistant foam directly on spill. Use a high-expansion foam if available to reduce vapors. Prevent spreading of vapors through sewers, ventilation systems and confined areas. Isolate area until gas has dispersed. CAUTION: When in contact with refrigerated/cryogenic liquids, many materials become brittle and are likely to break without warning. (ERG, 2024)

Fireproof. Cool. Ventilation along the floor and ceiling.

Store in a cool, dry, well-ventilated location. Separate from halogens and oxygen. Outside or detached storage is preferred.

Protect against physical damage. ... Isolate from oxidizing agents. Prohibit open flame. Inspect for leakage occasionally.

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.

· Always wear thermal protective clothing when handling refrigerated/cryogenic liquids.

2292 [ppm]

25000 [ppm]

150000 [ppm]

Minimal Oxygen Content. ACGIH recommends a minimal ambient oxygen partial pressure of 132 torr, which is protective against inert oxygen-displacing gases and oxygen-consuming processes for altitudes up to 5000 feet.

· DO NOT EXTINGUISH A LEAKING GAS FIRE UNLESS LEAK CAN BE STOPPED.

CAUTION: Hydrogen (UN1049), Deuterium (UN1957), Hydrogen, refrigerated liquid (UN1966) and Hydrogen and Methane mixture, compressed (UN2034) will burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.)

Small Fire

· Dry chemical or CO2.

Large Fire

· Water spray or fog.

· If it can be done safely, move undamaged containers away from the area around the fire.

CAUTION: For LNG - Liquefied natural gas (UN1972) pool fires, DO NOT USE water. Use dry chemical or high-expansion foam.

Fire Involving Tanks

· Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.

· Cool containers with flooding quantities of water until well after fire is out.

· Do not direct water at source of leak or safety devices; icing may occur.

· Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.

· ALWAYS stay away from tanks in direct contact with flames.

· For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn.

On loss of containment this substance can cause suffocation by lowering the oxygen content of the air in confined areas.

Rapid evaporation of the liquid may cause frostbite.

Self-contained breathing apparatus; protective clothing if exposed to liquid. (USCG, 1999)

Self-contained breathing apparatus for high concentrations; protective clothing if exposed to liquid. (USCG, 1999)

Excerpt from ERG Guide 115 [Gases - Flammable (Including Refrigerated Liquids)]:

Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing provides thermal protection but only limited chemical protection. Always wear thermal protective clothing when handling refrigerated/cryogenic liquids. (ERG, 2024)

Skin and body protection: Impervious clothing, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.

Eye protection: Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

Hand protection: Handle with gloves.

Respiratory protection: Where risk assessment shows air-purifying respirators are appropriate use a full-face respirator with multi-purpose combination (US) or type AXBEK (EN 14387) respirator cartridges as a backup to engineering controls. If the respirator is the sole means of protection, use a full-face supplied air respirator. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).

NO open flames, NO sparks and NO smoking. Closed system, ventilation, explosion-proof electrical equipment and lighting. Use non-sparking handtools.

Use ventilation. Use breathing protection.

Cold-insulating gloves.

Wear safety goggles.

Methane is a colorless odorless gas. It is also known as marsh gas or methyl hydride. It is easily ignited. The vapors are lighter than air. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. It is used in making other chemicals and as a constituent of the fuel, natural gas.

Methane, refrigerated liquid (cryogenic liquid) is a colorless odorless liquid. Flammable. Water insoluble.

Natural gas, [compressed] appears as a flammable gaseous mixture of straight chain hydrocarbons, predominately compressed methane.

Liquid; CBI; Gas Vapor

Colorless, odorless gas; [Merck Index] Vapor density = 0.554 (lighter than air); [HSDB]

COLOURLESS ODOURLESS COMPRESSED OR LIQUEFIED GAS.

Colorless gas

Odorless

Weak odor

Tasteless

-258 °F at 760 mmHg (USCG, 1999)

-258.7 °F at 760 mmHg (NTP, 1992)

-161.50 °C

-161.48 °C @760 [mm Hg]

-296 °F (USCG, 1999)

-296.5 °F (NTP, 1992)

-182.566 °C

-182.4 °C

-182.47 °C

-306 °F (NTP, 1992)

-188 °C (-306 °F) - closed cup

Flammable gas

3.5 mL/100 mL at 63 °F (NTP, 1992)

In water, 22 mg/L at 25 °C

Slightly soluble in acetone; soluble in ethanol, ethyl ether, benzene, toluene, methanol

0.91 mL in 1 g ether at 20 °C; 0.60 mL in 1 g ethyl alcohol at 20 °C

0.022 mg/mL at 25 °C

Solubility in water, ml/100ml at 20 °C: 3.3

0.415 to 0.45 at -259.6 °F (USCG, 1999)

0.422 at -256 °F (USCG, 1999) - Less dense than water; will float

0.554 at 0 °C/4 °C (air = 1 ) or 0.7168 g/liter

0.4228 @ -162°C

0.55 (NTP, 1992) - Lighter than air; will rise (Relative to Air)

0.554 at 0 °C (Air = 1)

Relative vapor density (air = 1): 0.6

258574 mmHg at 100 °F ; 760 mmHg at -258.7 °F (NTP, 1992)

VP: 1 Pa at -220 °C (solid); -10 Pa at 214.2 °C (solid); 100 Pa at -206.8 °C (solid); 1 kPa at -197 °C (solid); 10 kPa at -183.6 °C (solid); 100 kPa at -161.7 °C

4.66X10+5 mm Hg at 25 °C

750 [mm Hg] @-161.69999999999999 °C

log Kow = 1.09

Highly flammable.

Highly flammable. Insoluble in water.

Hydrocarbons, Aliphatic Saturated

Highly Flammable

Strong Reducing Agent

Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container [Handling Chemicals Safely 1980].

METHANE is a reducing agent, it is involved in many explosions when combined with especially powerful oxidizers such as bromine pentafluoride, chlorine trifluoride, chlorine, iodine, heptafluoride, dioxygenyl tetrafluoroborate, dioxygen difluoride, trioxygen difluoride and liquid oxygen. Other violent reactions include, chlorine dioxide and nitrogen trifluoride. Liquid oxygen gives an explosive mixture when combined with liquid methane [NFPA 1991]. Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container [Handling Chemicals Safely 1980].

Liquid oxygen gives an explosive mixture when combined with liquid methane [NFPA 1991]. Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container [Handling Chemicals Safely 1980]. Involved in many explosions when combined with especially powerful oxidizers such as bromine pentafluoride, chlorine trifluoride, chlorine, iodine, heptafluoride, dioxygenyl tetrafluoroborate, dioxygen difluoride, trioxygen difluoride and liquid oxygen. Other violent reactions include, chlorine dioxide and nitrogen trifluoride.

... Reacts with chlorine and bromine in light (explosively in direct sunlight)

Explosive reactions occur upon ignition of mixtures of nitrogen trifluoride with good reducing agents such as ... methane.

Liquid oxygen gives an explosive mixture when combined with liquid methane.

The reaction of chlorine and methane is explosive at room temperature over yellow mercuric oxide.

For more Hazardous Reactivities and Incompatibilities (Complete) data for METHANE (14 total), please visit the HSDB record page.

Methane is an asphyxiant and displaces oxygen in enclosed spaces. At high enough concentrations, oxygen depletion may cause asphyxiation. Low concentrations of surrounding oxygen results in deficient oxygen to the organs, compounded by increased oxygen exhalation during respiration. This results in generalized hypoxia and possibly death. (L171, A120)

No indication of carcinogenicity to humans (not listed by IARC).

Methane is an asphyxiant and displaces oxygen in enclosed spaces. At high enough concentrations, oxygen depletion may cause asphyxiation, resulting in generalized hypoxia and possibly death. (L171, L172)

The substance can be absorbed into the body by inhalation.

Inhalation (L172)

Suffocation.

ON CONTACT WITH LIQUID: FROSTBITE.

Symptoms of methane asphyxiation include nausea, vomiting, difficulty breathing, irregular heartbeat, headache, drowsiness, fatigue, dizziness, disorientation, mood swings, tingling sensation, loss of coordination,

suffocation, convulsions, unconsciousness, coma, and possibly death. (L173)

Other Poison - Simple Asphyxiant

LC50: 326 gm/m3 over 2 hours (Inhalation, Mouse) (L173)

Asphyxiation should be treated by moving the affected person to an uncontaminated area, then giving artificial respiration and administering oxygen, if necessary. (L173)

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on the left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Aliphatic hydrocarbons and related compounds/

Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . Treat frostbite with rapid rewarming techniques ... ./Aliphatic hydrocarbons and related compounds/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag-valve-mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously.Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Aliphatic hydrocarbons and related compounds/

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Simple asphyxiants and related compounds/

For more Antidote and Emergency Treatment (Complete) data for METHANE (6 total), please visit the HSDB record page.

/HUMAN EXPOSURE STUDIES/ ...May cause frostbite /like effects/ on skin contact. /Liquified methane/

/HUMAN EXPOSURE STUDIES/ ... Methane... acts as a simple asphyxiant when inhaled. /Its/ presence displaces air, which lowers the partial pressure of oxygen and causes hypoxia.

/CASE REPORTS/ It has been known that methane gas intoxication causes loss of consciousness or asphyxia. There is, however, a paucity of information about acute pulmonary toxicity from methane gas inhalation. A 21-year-old man was presented with respiratory distress after an accidental exposure to methane gas for one minute. He came in with a drowsy mentality and hypoxemia. Mechanical ventilation was applied immediately. The patient's symptoms and chest radiographic findings were consistent with acute pneumonitis. He recovered spontaneously and was discharged after 5 days without other specific treatment. His pulmonary function test, 4 days after methane gas exposure, revealed a restrictive ventilatory defect. In conclusion, acute pulmonary injury can occur with a restrictive ventilator defect after a short exposure to methane gas. The lung injury was spontaneously resolved without any significant sequela.

/OTHER TOXICITY INFORMATION/ The impact of major gaseous and particulate pollutants emitted by the wildfire of October 2003 on ambient air quality and health of San Diego residents before, during, and after the fire are analyzed using data available from the San Diego County Air Pollution Control District and California Air Resources Board. It was found that fine particulate matter (PM) levels exceeded the federal daily 24-hr average standard during the fire. There was a slight increase in some of the gaseous pollutants, such as carbon monoxide, which exceeded federal standards. Ozone (O3) precursors, such as total hydrocarbons and methane gases, experienced elevated concentration during the fire. Fortunately, the absence of sunlight because of the cloud of thick smoke that covered most of the county during the fire appears to have prevented the photochemical conversion of the precursor gases to harmful concentrations of O3. Statistical analysis of the compiled medical surveillance data has been used to establish correlations between pollutant levels in the region and the resultant health problems experienced by the county citizens. The study shows that the increased PM concentration above the federal standard resulted in a significant increase in hospital emergency room visits for asthma, respiratory problems, eye irritation, and smoke inhalation...

/OTHER TOXICITY INFORMATION/ A simple asphyxiant.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ Because it is biologically inert, Toxicity occurs only when its presence reduces or eliminates the oxygen in the environment. Rabbits can inhale a mixture of one volume of oxygen and four volumes of methane for any length of time without showing any ill effects.

/LABORATORY ANIMALS: Developmental or Reproductive Toxicity/ ...Pregnant mice /were exposed/ on the 8th day for 1 hr to 5-8% concentration of fuel gas. In addition to 85% methane most natural gases contain small amounts of ethane, propane and butane. Abnormalities of the fetal brains were found to result in brain hernia and hydrocephalus.

/OTHER TOXICITY INFORMATION/ The inhibitory action of compressed hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated quantitatively by microcalorimetry. Both the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP), which are regarded as indices of the toxicity of hydrocarbon gases, were determined from growth thermograms. Based on these values, the inhibitory potency of the hydrocarbon gases increased in the order methane << ethane < propane < i-butane < n-butane. The toxicity of these hydrocarbon gases correlated to their hydrophobicity, suggesting that hydrocarbon gases interact with some hydrophobic regions of the cell membrane. In support of this, /the authors/ found that UV absorbing materials at 260 nm were released from yeast cells exposed to compressed hydrocarbon gases. Additionally, scanning electron microscopy indicated that morphological changes occurred in these cells.

Methane is the principal constituent of natural gas (85%) and is also a major greenhouse gas found in the atmosphere. It is released to the environment as natural emissions from microbes, animal waste, and volcanos. Other important sources of methane is the rumen of domestic animals (especially cattle) and emissions during the growing of rice. Methane is stored as methane hydrates in immense amounts both in Arctic regions and in marine sediments. The worldwide amounts of methane hydrates are conservatively estimated to total twice the amount of carbon found in all known fossil fuels on earth. Methane may be released as a fugitive emission from hydrofracking gas processing equipment. The compound's production and use in synthesis gas production, in manufacture of hydrogen, hydrogen cyanide, ammonia, acetylene, formaldehyde, and in organic syntheses may result in its release to the environment through various waste streams. Its use as a constituent of illuminating and cooking gas will result in its direct release to the environment. Direct release of methane to the environment will also occur due to hydrocarbon venting and water discharges from offshore production operations, two major sources of methane. Methane gas is a major product in sludge digestion with sludge gas consisting of 65-70% methane. Methane may be released to the environment as emissions from coal outgassing, combustion and liquefaction, and as emissions from waste incineration. Methane may be released to the environment as emissions from automobile, turbine and diesel exhaust. Methane may be released to the environment as emissions from biomass and polymer combustion, foundries, sewage and water treatment, veneer drying and wood pulping, and landfills. If released to air, a vapor pressure of 4.66X10+5 mm Hg at 25 °C indicates methane will exist solely as a gas in the atmosphere. Gas-phase methane will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 4 yrs. Methane does not contain chromophores that absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, methane is expected to have very high mobility based upon an estimated Koc of 9. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 0.66 atm-cu m/mole. Methane may volatilize from dry soil surfaces based upon its vapor pressure. An average utilization of 55% for methane by anaerobic soil microorganisms suggests that biodegradation may be an environmental fate process in soil. If released into water, methane is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. Biodegradation half-lives were estimated to range from 70 days to infinity using anaerobic model estuarine ecosystems, indicating that biodegradation is not an important environmental fate process in water. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. An estimated BCF of 2 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions (pH 5 to 9). Occupational exposure to methane may occur through inhalation of this compound at workplaces where methane is produced or used. Monitoring data indicate that the general population may be exposed to methane via inhalation of ambient air. (SRC)

Methane may be released to the environment as emissions from microbes, animal waste and volcanoes(1,2). Methane is the principal constituent of natural gas(1,3); natural gas from America is approximately 85% methane(4). Emissions of geothermal steam may release methane to the environment(1,5). Methane is a constituent of petroleum gases(6). An important source of methane is the rumen of domestic animals, especially of cattle(7). Methane may be released to the environment through emissions during the growing of rice(7).

Methane is found as hydrates (i.e., methane hydrate) in immense amounts both in Arctic regions and in marine sediments(1). Methane hydrate is stable in ocean floor sediments at water depths greater than 300 meters, and where it occurs, it is known to cement loose sediments in a surface layer several hundred meters thick(1). The worldwide amounts of carbon bound as gas hydrates (e.g., methane hydrate) is conservatively estimated to total twice the amount of carbon found in all known fossil fuels on Earth(1). The earth's atmosphere contains 0.00022% methane by volume(2).

Potential rates of methane generation and carbon dioxide generation were measured on 11 dates in 1986 in peat from six plant communities typical of moss dominated peatlands in the Appalachian Mountains(1). Annual methane generation ranged from 2.7 to 17.5 M/sq m, and annual carbon dioxide production ranged from 30.6 to 79.0 M/sq m(1). The wide range in methane generation values among the communities found within a single peatland indicates that obtaining one generation value for a peatland may not be appropriate(1). Low temperature constrained the potential for methane generation in winter, while the chemical quality of the peat substrate appears to control methane generation in the summer(1). Methane oxidation was measured throughout the peat profile to a depth of 30 cm(1). Values for methane oxidation ranged from 0.08 to 18.7 uM/hr among the six plant communities(1). Aerobic methane oxidizing bacteria probably mediated most of the activity(1). On a daily basis during the summer, between 11 and 100% of the methane generated is susceptible to oxidation within the peat column(1). Pools of dissolved methane and dissolved carbon dioxide in pore waters were <0.2 and <1.0 M/sq m, respectively, indicating that methane does not accumulate in the pore waters. Peatlands have been considered as an important source of biologically produced methane(1). Despite the high rates of methane generation, the high rates of methane oxidation dampen the potential emission of methane to the atmosphere(1).

C(14) content of atmospheric methane prior to nuclear adn thermal nuclear bomb-testing contamination suggests that greater than 80% of atmospheric methane is from decay of recent organic matter. /14(C)-Methane/

Methane's production and use in synthesis gas production(1), in manufacture of hydrogen, hydrogen cyanide, ammonia, acetylene, formaldehyde, and in organic syntheses(2) may result in its release to the environment through various waste streams(SRC). Its use as a constituent of illuminating and cooking gas(2) will result in its direct release to the environment(SRC). Natural gas production from hydrocarbon-rich shale formations, known as "shale gas" is one of the most rapidly expanding trends in on-shore domestic oil and gas exploration and production today. Natural gas supplies about 22% of the total US energy demands. Methane is the principle component of natural gas and a known Greenhouse Gas. Methane may be released as a fugitive emission from gas processing equipment(3).

Direct release of methane to the environment will also occur due to hydrocarbon venting and water discharges from offshore production operations, two major sources of methane(1). Methane gas is a major product in sludge digestion with sludge gas consisting of 65-70% methane(2,3). Methane may be released to the environment as emissions from coal outgassing, combustion and liquefaction(4-6). Methane may be released to the environment as emissions from waste incineration (2,7,8). Methane may be released to the environment as emissions from automobile, turbine and diesel exhaust(4,9,10). Methane may be released to the environment as emissions from biomass and polymer combustion, foundries, sewage and water treatment, veneer drying and wood pulping(2), and landfills(11). The compound is generated as a result of biodegradation of short-chain n-alkanes in oil sand tailings under methanogenic conditions(12).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 9(SRC), determined from a log Kow of 1.09(2) and a regression-derived equation(3), indicates that methane is expected to have very high mobility in soil(SRC). Volatilization of methane from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 0.66 atm-cu m/mole(SRC), derived from its vapor pressure, 4.66X10+5 mm Hg(4), and water solubility, 22 mg/L(5). Methane is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). An average utilization of 55% for methane by anaerobic soil microorganisms(6) suggests that biodegradation may be an environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 9(SRC), determined from a log Kow of 1.09(2) and a regression-derived equation(3), indicates that methane is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon an estimated Henry's Law constant of 0.66 atm-cu m/mole(SRC), derived from its vapor pressure, 4.66X10+5 mm Hg(5), and water solubility, 22 mg/L(6). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 2 hours(SRC). According to a classification scheme(7), an estimated BCF of 2(SRC), from its log Kow(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low(SRC). The biodegradation half-life of methane was estimated to range from 70 days to infinity in model anaerobic estuarine ecosystems(8), indicating that biodegradation is not an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methane, which has a vapor pressure of 4.66X10+5 mm Hg at 25 °C(2), is expected to exist solely as a gas in the ambient atmosphere. Gas-phase methane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 4 yrs(3), calculated from its rate constant of 6.85X10-15 cu cm/molecule-sec at 25 °C(4). Methane does not contain chromophores that absorb at wavelengths >290 nm(5) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

ANAEROBIC: Utilization of methane by soil microorganisms has been detected using five enriched soil samples collected from sites near Adelaide, South Australia; an average methane utilization of 55% was observed over 69 days. Methane utilization, expressed as % of control were as follows (value (soil type): 10 (litchfield podzolic, pH 5.9, 14% clay, 2.3% organic carbon, 17% moisture); 73 (pond mud, pH 7.9, 49% clay, 2.5% organic carbon, 126% moisture3); 55 (red brown earth, pH 7.7, 16% clay, 2.4% organic carbon, 8% moisture); 61 (Grey clay, pH 8.0, 36% clay, 3.1% organic carbon, 41% moisture); 75 (siliceous sands, pH 5.1, 5% clay, 2.4% organic carbon, 19% moisture)(1). The half-life of methane was estimated to range from 70 days to infinity based on gas exchange biodegradation experiments conducted in model estuarine ecosystems; inoculum sediments were obtained from Narragansett Bay, RI(2).

The rate constant for the vapor-phase reaction of methane with photochemically-produced hydroxyl radicals is 6.86X10-15 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 4 years at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(2). Methane is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). Methane does not contain chromophores that absorb at wavelengths >290 nm(3) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

Evidence of methane oxidation was seen in lakes impacted by the May 18, 1980 eruption of Mount St. Helens in Washington state during the summer of 1981, and rates of methane oxidation using 14C-methane were measured in Spirit Lake from 1982 to 1986. The highest rates of methane oxidation measured were during the summer stratification and ranged from 50 to 150 nM methane oxidized/L/day. Methane oxidation rates were measured in waters having oxygen concentrations <100 uM with highest activity occurring at concentrations of 30-60 uM. Spirit Lake samples taken during 1986 showed a marked reduction in the levels of methane. This has corresponded with a marked reduction in the levels of dissolved organic material in the lake and an apparent decline in sedimentary methanogenesis.

An estimated BCF of 2 was calculated in fish for methane(SRC), using a log Kow of 1.09(1) and a regression-derived equation(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Koc of methane is estimated as 9(SRC), using a log Kow of 1.09(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that methane is expected to have very high mobility in soil. Methane's vapor pressure of 4.7X10+5 mm Hg(4) suggests that this compound will permeate through soil(SRC).

The Henry's Law constant for methane is estimated as 0.66 atm-cu m/mole(SRC) derived from its vapor pressure, 4.66X10+5 mm Hg(1), and water solubility, 22 mg/L(2). This Henry's Law constant indicates that methane is expected to volatilize rapidly from water surfaces(3). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 2 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 2 hours(SRC). Methane's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). The potential for volatilization of methane from dry soil surfaces may exist(SRC) based upon the vapor pressure(1).

Methane is the principal constituent of natural gas (85%) and is also a major greenhouse gas found in the atmosphere. It is released to the environment as natural emissions from microbes, animal waste, and volcanos. Other important sources of methane is the rumen of domestic animals (especially cattle) and emissions during the growing of rice. Methane is stored as methane hydrates in immense amounts both in Arctic regions and in marine sediments. The worldwide amounts of methane hydrates are conservatively estimated to total twice the amount of carbon found in all known fossil fuels on earth. Methane may be released as a fugitive emission from hydrofracking gas processing equipment. The compound's production and use in synthesis gas production, in manufacture of hydrogen, hydrogen cyanide, ammonia, acetylene, formaldehyde, and in organic syntheses may result in its release to the environment through various waste streams. Its use as a constituent of illuminating and cooking gas will result in its direct release to the environment. Direct release of methane to the environment will also occur due to hydrocarbon venting and water discharges from offshore production operations, two major sources of methane. Methane gas is a major product in sludge digestion with sludge gas consisting of 65-70% methane. Methane may be released to the environment as emissions from coal outgassing, combustion and liquefaction, and as emissions from waste incineration. Methane may be released to the environment as emissions from automobile, turbine and diesel exhaust. Methane may be released to the environment as emissions from biomass and polymer combustion, foundries, sewage and water treatment, veneer drying and wood pulping, and landfills. If released to air, a vapor pressure of 4.66X10+5 mm Hg at 25 °C indicates methane will exist solely as a gas in the atmosphere. Gas-phase methane will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 4 yrs. Methane does not contain chromophores that absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, methane is expected to have very high mobility based upon an estimated Koc of 9. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 0.66 atm-cu m/mole. Methane may volatilize from dry soil surfaces based upon its vapor pressure. An average utilization of 55% for methane by anaerobic soil microorganisms suggests that biodegradation may be an environmental fate process in soil. If released into water, methane is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. Biodegradation half-lives were estimated to range from 70 days to infinity using anaerobic model estuarine ecosystems, indicating that biodegradation is not an important environmental fate process in water. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. An estimated BCF of 2 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions (pH 5 to 9). Occupational exposure to methane may occur through inhalation of this compound at workplaces where methane is produced or used. Monitoring data indicate that the general population may be exposed to methane via inhalation of ambient air. (SRC)

Methane may be released to the environment as emissions from microbes, animal waste and volcanoes(1,2). Methane is the principal constituent of natural gas(1,3); natural gas from America is approximately 85% methane(4). Emissions of geothermal steam may release methane to the environment(1,5). Methane is a constituent of petroleum gases(6). An important source of methane is the rumen of domestic animals, especially of cattle(7). Methane may be released to the environment through emissions during the growing of rice(7).

Methane is found as hydrates (i.e., methane hydrate) in immense amounts both in Arctic regions and in marine sediments(1). Methane hydrate is stable in ocean floor sediments at water depths greater than 300 meters, and where it occurs, it is known to cement loose sediments in a surface layer several hundred meters thick(1). The worldwide amounts of carbon bound as gas hydrates (e.g., methane hydrate) is conservatively estimated to total twice the amount of carbon found in all known fossil fuels on Earth(1). The earth's atmosphere contains 0.00022% methane by volume(2).

Potential rates of methane generation and carbon dioxide generation were measured on 11 dates in 1986 in peat from six plant communities typical of moss dominated peatlands in the Appalachian Mountains(1). Annual methane generation ranged from 2.7 to 17.5 M/sq m, and annual carbon dioxide production ranged from 30.6 to 79.0 M/sq m(1). The wide range in methane generation values among the communities found within a single peatland indicates that obtaining one generation value for a peatland may not be appropriate(1). Low temperature constrained the potential for methane generation in winter, while the chemical quality of the peat substrate appears to control methane generation in the summer(1). Methane oxidation was measured throughout the peat profile to a depth of 30 cm(1). Values for methane oxidation ranged from 0.08 to 18.7 uM/hr among the six plant communities(1). Aerobic methane oxidizing bacteria probably mediated most of the activity(1). On a daily basis during the summer, between 11 and 100% of the methane generated is susceptible to oxidation within the peat column(1). Pools of dissolved methane and dissolved carbon dioxide in pore waters were <0.2 and <1.0 M/sq m, respectively, indicating that methane does not accumulate in the pore waters. Peatlands have been considered as an important source of biologically produced methane(1). Despite the high rates of methane generation, the high rates of methane oxidation dampen the potential emission of methane to the atmosphere(1).

C(14) content of atmospheric methane prior to nuclear adn thermal nuclear bomb-testing contamination suggests that greater than 80% of atmospheric methane is from decay of recent organic matter. /14(C)-Methane/

Methane's production and use in synthesis gas production(1), in manufacture of hydrogen, hydrogen cyanide, ammonia, acetylene, formaldehyde, and in organic syntheses(2) may result in its release to the environment through various waste streams(SRC). Its use as a constituent of illuminating and cooking gas(2) will result in its direct release to the environment(SRC). Natural gas production from hydrocarbon-rich shale formations, known as "shale gas" is one of the most rapidly expanding trends in on-shore domestic oil and gas exploration and production today. Natural gas supplies about 22% of the total US energy demands. Methane is the principle component of natural gas and a known Greenhouse Gas. Methane may be released as a fugitive emission from gas processing equipment(3).

Direct release of methane to the environment will also occur due to hydrocarbon venting and water discharges from offshore production operations, two major sources of methane(1). Methane gas is a major product in sludge digestion with sludge gas consisting of 65-70% methane(2,3). Methane may be released to the environment as emissions from coal outgassing, combustion and liquefaction(4-6). Methane may be released to the environment as emissions from waste incineration (2,7,8). Methane may be released to the environment as emissions from automobile, turbine and diesel exhaust(4,9,10). Methane may be released to the environment as emissions from biomass and polymer combustion, foundries, sewage and water treatment, veneer drying and wood pulping(2), and landfills(11). The compound is generated as a result of biodegradation of short-chain n-alkanes in oil sand tailings under methanogenic conditions(12).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 9(SRC), determined from a log Kow of 1.09(2) and a regression-derived equation(3), indicates that methane is expected to have very high mobility in soil(SRC). Volatilization of methane from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 0.66 atm-cu m/mole(SRC), derived from its vapor pressure, 4.66X10+5 mm Hg(4), and water solubility, 22 mg/L(5). Methane is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). An average utilization of 55% for methane by anaerobic soil microorganisms(6) suggests that biodegradation may be an environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 9(SRC), determined from a log Kow of 1.09(2) and a regression-derived equation(3), indicates that methane is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon an estimated Henry's Law constant of 0.66 atm-cu m/mole(SRC), derived from its vapor pressure, 4.66X10+5 mm Hg(5), and water solubility, 22 mg/L(6). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 2 hours(SRC). According to a classification scheme(7), an estimated BCF of 2(SRC), from its log Kow(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low(SRC). The biodegradation half-life of methane was estimated to range from 70 days to infinity in model anaerobic estuarine ecosystems(8), indicating that biodegradation is not an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methane, which has a vapor pressure of 4.66X10+5 mm Hg at 25 °C(2), is expected to exist solely as a gas in the ambient atmosphere. Gas-phase methane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 4 yrs(3), calculated from its rate constant of 6.85X10-15 cu cm/molecule-sec at 25 °C(4). Methane does not contain chromophores that absorb at wavelengths >290 nm(5) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

ANAEROBIC: Utilization of methane by soil microorganisms has been detected using five enriched soil samples collected from sites near Adelaide, South Australia; an average methane utilization of 55% was observed over 69 days. Methane utilization, expressed as % of control were as follows (value (soil type): 10 (litchfield podzolic, pH 5.9, 14% clay, 2.3% organic carbon, 17% moisture); 73 (pond mud, pH 7.9, 49% clay, 2.5% organic carbon, 126% moisture3); 55 (red brown earth, pH 7.7, 16% clay, 2.4% organic carbon, 8% moisture); 61 (Grey clay, pH 8.0, 36% clay, 3.1% organic carbon, 41% moisture); 75 (siliceous sands, pH 5.1, 5% clay, 2.4% organic carbon, 19% moisture)(1). The half-life of methane was estimated to range from 70 days to infinity based on gas exchange biodegradation experiments conducted in model estuarine ecosystems; inoculum sediments were obtained from Narragansett Bay, RI(2).

The rate constant for the vapor-phase reaction of methane with photochemically-produced hydroxyl radicals is 6.86X10-15 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 4 years at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(2). Methane is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). Methane does not contain chromophores that absorb at wavelengths >290 nm(3) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

Evidence of methane oxidation was seen in lakes impacted by the May 18, 1980 eruption of Mount St. Helens in Washington state during the summer of 1981, and rates of methane oxidation using 14C-methane were measured in Spirit Lake from 1982 to 1986. The highest rates of methane oxidation measured were during the summer stratification and ranged from 50 to 150 nM methane oxidized/L/day. Methane oxidation rates were measured in waters having oxygen concentrations <100 uM with highest activity occurring at concentrations of 30-60 uM. Spirit Lake samples taken during 1986 showed a marked reduction in the levels of methane. This has corresponded with a marked reduction in the levels of dissolved organic material in the lake and an apparent decline in sedimentary methanogenesis.

An estimated BCF of 2 was calculated in fish for methane(SRC), using a log Kow of 1.09(1) and a regression-derived equation(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Koc of methane is estimated as 9(SRC), using a log Kow of 1.09(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that methane is expected to have very high mobility in soil. Methane's vapor pressure of 4.7X10+5 mm Hg(4) suggests that this compound will permeate through soil(SRC).

The Henry's Law constant for methane is estimated as 0.66 atm-cu m/mole(SRC) derived from its vapor pressure, 4.66X10+5 mm Hg(1), and water solubility, 22 mg/L(2). This Henry's Law constant indicates that methane is expected to volatilize rapidly from water surfaces(3). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 2 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 2 hours(SRC). Methane's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). The potential for volatilization of methane from dry soil surfaces may exist(SRC) based upon the vapor pressure(1).

Methane emissions to the atmosphere was studied in the deepest, central (pelagic) regions of one freshwater and three meromictic, alkaline saline lakes. The range of methane emissions was 0.0004 to 2.916 mM/sq m/hr (n = 41). Outward flux was dominated by bubble ebullition only in the freshwater lake. Diffusive gas exchange was the sole mechanism of transfer in the meromictic lakes, and flux from these lakes was equivalent to or lower than that from the freshwater lake during its periods of ebullition. A comparison of measured flux with flux calculated using a model of gas exchange in Mono Lake suggested that floating chambers provide reasonable estimates of the magnitude of methane emissions form diffusion-dominated systems.

GROUNDWATER: Methane was detected in three of eleven bedrock domestic wells near the Granby, CT landfill at concentrations of 240 ppb, 10,000 ppb and an unspecified high concentration.

DRINKING WATER: Methane has been identified in drinking water in the United States(1).

SURFACE WATER: The concentrations of methane and methane oxidation rates were measured in lakes impacted by the May 18, 1980 eruption of Mount St. Helens(1). The highest methane concentrations were recorded during the first summer after the eruption and ranged in surface waters from 5 uM in the moderately impacted Ryan Lake to 28 uM in the heavily impacted North Coldwater Lake(1). At depths below the oxic/anoxic interface, methane levels reached 250 uM in North Coldwater Lake, 184 uM in Spirit Lake, 70 uM in Castle Creek Lake, and 60 uM in Ryan Lake(1). The methane flux measurements from these lakes during the summer following the May 18, 1980 eruption were the highest ever recorded in lakes with ranges of 1.1-2.9 mM CH4/sq m/day in the light to moderately impacted McBride and Ryan Lakes to ranges of 17.4-25.3 mM methane/sq m/day in the heavily impacted Castle Creek, North Coldwater, and Spirit Lakes(1).

SURFACE WATER: Methane was detected in surface water at nine dump sites of municipal and industrial wastes in the western Gulf of Mexico at concentrations ranging from 55 to 667 nL/L(1). Methane concentrations of 42 to 370 nL/L have been detected from six stations in south Texas coastal waters(2).

In exhaust of diesel engine: 17% of emitted hydrocarbons; in exhaust of reciprocating gasoline engine: 24% of emitted hydrocarbons; in exhaust of rotary gasoline engine: 4.9% of emitted hydrocarbons; expected glc's in USA urgan air: range: 1.6-10 ppm; in combustion gas of household central heating on gasoil: 20 ppm; in flue gas of municipal incinerator: < 0.4-13.0 ppm; in exhaust of gasoline engine: 14-17% of total exhaust hydrocarbons; 15 fuel survey: 18 vol % of total exhaust hydrocarbons

In 1990, emissions of methane to the atmosphere were approximately 380 million tons/yr; in 1860, 80 million tons/yr of methane were released(1). Methane emissions estimates for 1993 were as follows: gas flaring, 18.0X10+12 g/yr; gas supply, 16.9X10+12 g/yr; coal mining 46.3X10+12 g/yr; biomass burning, 38.4X10+12 g/yr; livestock, 112.1X10+12 g/yr; rice, 101.4X10+12 g/yr; landfills, 43.9X10+12 g/yr(1). Methane emissions estimates for 1860 were as follows: gas flaring, 0.0X10+12 g/yr; gas supply, 0.0X10+12 g/yr; coal mining 2.2X10+12 g/yr; biomass burning, 9.8X10+12 g/yr; livestock, 25.6X10+12 g/yr; rice, 40.1X10+12 g/yr; landfills, 1.6X10+12 g/yr(1). Livestock farming is the largest anthropogenic source of methane(1).

Methane was detected in the flue gas of an incineration plant located in the town of Babylon, NY during three different tests at concentrations ranging from less than 0.4 to 13.0 ppm(1). Methane was found in combustion gas of light fuel oil at concentrations ranging from 0.32 to 26.80 mL/L and it was detected in the exhaust gas of light fuel oil at a concentration of 0.11 mL/L(2). Automotive exhaust emissions have been found to contain methane(6,7). It was found to be present in effluents from coal combustion(3). Methane was detected in ten samples of emissions from jet engines at concentrations ranging from 0.05 to 48.0 ppm(4). Wood smoke has been found to contain methane in the gas-phase at final concentrations of 4,500 and 3,920 ppb(5). Methane was detected in the ambient air of five California landfills at concentrations ranging from 16,600 to 587,000 ppm(8). The rate of methane from fireplace combustion of wood was 4,120 mg/kg wood burned(9). The concentration of methane measured in the Caldecott Tunnel located in San Francisco Bay, CA was approx 413 mg/L during a period when low oxygenated fuel was used(10). When high oxygenated fuel was used, the concentration of methane in tunnel air was about 459 mg/L(10).

Direct measurement of methane (CH4) flux from wetland ecosystems of south Florida demonstrates that freshwater wet prairies and inundated sawgrass marsh are the dominant sources of atmospheric CH4 in the region(1). Fluctuations in soil moisture are an important environmental factor controlling both seasonal and interannual fluctuations in CH4 emissions from undisturbed wetlands(1). Land use estimates for 1900 and 1973 were used to calculate regional CH4 flux(1). Human settlement in south Florida has modified wetland sources of CH4, reducing the natural prairies and marsh sources by 37%(1). During the same period, impoundments and disturbed wetlands were created which produce CH4 at rates approximately 50% higher than the natural wetlands they replaced(1). The mean standard error, in mg methane/sq m/day, was 61 for wet prairies and sawgrass marsh, 59 for wetland forests, 4 for saltwater mangroves, and 74 for impoundments and disturbed wetlands(1).

SEDIMENT: Methane flux and the stable isotopic composition of sedimentary methane were measured at four locations in the Florida Everglades system. Individual estimates of methane flux ranged over more than 3 orders of magnitude, from about 0.001 to 2.6 mg/sq m/day. Significant interstation differences in total methane flux were observed and judged to be most likely due to differences in the size and spacing of emergent aquatic vegetation, and possibly differences in the type of organic matter incorporated into the sediments. The C(13) mean delta of sedimentary methane samples measured in the Everglades system (61.7 parts per trillion, standard deviation = 3.6 parts per trillion, n = 51) was not significantly different from the estimated C(13) average delta of all natural sources (-58.3 parts per trillion).

SEDIMENT: Methane has been detected in sediment from the shelf, slope, and basin of the Bering Sea at concentrations ranging from 1300 to 13000 nL/L, 700 to 8400 nL/L, and 300 to 21000 nL/L, respectively.

A factor of 2.5 increase in the global abundance of atmospheric methane (CH(4)) since 1750 contributes 0.5 Wm(-2) to total direct radiative forcing by long-lived greenhouse gases (2.77 Wm(-2) in 2009), while its role in atmospheric chemistry adds another approximately 0.2 Wm(-2) of indirect forcing. Since CH(4) has a relatively short lifetime and it is very close to a steady state, reductions in its emissions would quickly benefit climate. Sensible emission mitigation strategies require quantitative understanding of CH(4)'s budget of emissions and sinks. Atmospheric observations of CH(4) abundance and its rate of increase, combined with an estimate of the CH(4) lifetime, constrain total global CH(4) emissions to between 500 and 600 Tg CH(4) yr(-1). While total global emissions are constrained reasonably well, estimates of emissions by source sector vary by up to a factor of 2. Current observation networks are suitable to constrain emissions at large scales (e.g. global) but not at the regional to national scales necessary to verify emission reductions under emissions trading schemes. Improved constraints on the global CH(4) budget and its break down of emissions by source sector and country will come from an enhanced observation network for CH(4) abundance and its isotopic composition (delta(13)C, deltaD(D=(2)H) and delta(14)C). Isotopic measurements are a valuable tool in distinguishing among various sources that contribute emissions to an air parcel, once fractionation by loss processes is accounted for. Isotopic measurements are especially useful at regional scales where signals are larger. Reducing emissions from many anthropogenic source sectors is cost-effective, but these gains may be cancelled, in part, by increasing emissions related to economic development in many parts of the world. An observation network that can quantitatively assess these changing emissions, both positive and negative, is required, especially in the context of emissions trading schemes.

Methane is an important greenhouse gas, and its atmospheric concentration has nearly tripled since pre-industrial times. The growth rate of atmospheric methane is determined by the balance between surface emissions and photochemical destruction by the hydroxyl radical, the major atmospheric oxidant. Remarkably, this growth rate has decreased markedly since the early 1990s, and the level of methane has remained relatively constant since 1999, leading to a downward revision of its projected influence on global temperatures. Large fluctuations in the growth rate of atmospheric methane are also observed from one year to the next, but their causes remain uncertain. Here we quantify the processes that controlled variations in methane emissions between 1984 and 2003 using an inversion model of atmospheric transport and chemistry. Our results indicate that wetland emissions dominated the inter-annual variability of methane sources, whereas fire emissions played a smaller role, except during the 1997-1998 El Nino event. These top-down estimates of changes in wetland and fire emissions are in good agreement with independent estimates based on remote sensing information and biogeochemical models. On longer timescales, our results show that the decrease in atmospheric methane growth during the 1990s was caused by a decline in anthropogenic emissions. Since 1999, however, they indicate that anthropogenic emissions of methane have risen again. The effect of this increase on the growth rate of atmospheric methane has been masked by a coincident decrease in wetland emissions, but atmospheric methane levels may increase in the near future if wetland emissions return to their mean 1990s levels.

URBAN/SUBURBAN: The concentration of methane measured at Exhibition Road, London, UK ranged from 1.34-2.45 ppm (average, 1.59 ppm) between the period of January 1991 to July 1992(1). Methane has been detected in five air samples collected in Houston, TX on April 2, 1974 at concentrations ranging from 1.91 to 2.31 ppm(2). Methane detected of Riverside, CA in smoggy air at 2.02 ppm(3).

URBAN/SUBURBAN: Methane emission in the Mexico City Metropolitan Area, 2000(1).

Table: Emission Inventory by Sector [Table#575]

For more Atmospheric Concentrations (Complete) data for METHANE (7 total), please visit the HSDB record page.

Geofluids are usually assumed to be saturated with methane with (6.9-8.9)X10-3 cu m methane/kg water(1). American natural gas is approximately 85% methane(2). Composition of typical natural gases are (vol%): 95.0 (Salt Lake, UT); 89.4 (Webb, TX); 65.8 (Klifside, TX); 93.2 (Sussex, England); 70.0 (Lacq, France)(3).

The methane emission factor of 14000 mg/kg at 1100 °C was measured in a laboratory-scale furnace using lignin samples, a sub-product in the Kraft process that is used to obtain cellullose by combustion of eucalyptus wood(1). Methane was released at an emmission factor range of 88,600-1,032,000 mg/kg as a result of pyrolysis of used cotton fabrics, a possible biomass fuel source(2).

Estimated emission factors for methane from fires in North America(1).[Table#577]

According to the 2006 TSCA Inventory Update Reporting data, the number of persons reasonably likely to be exposed in the industrial manufacturing, processing, and use of methane is 1000 or greater; the data may be greatly underestimated(1).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 65,649 workers (2,728 of these were female) were potentially exposed to methane in the US(1). Occupational exposure to methane may occur through inhalation of this compound at workplaces where methane is produced or used. Monitoring data indicate that the general population may be exposed to methane via inhalation of ambient air(SRC).

Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

/GUIDE 115: GASES - FLAMMABLE (INCLUDING REFRIGERATED LIQUIDS)/ Fire or Explosion: EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Vapors from liquefied gas are initially heavier than air and spread along ground. ... Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket. /Methane; Methane, compressed; Methane, refrigerated liquid (cryogenic liquid)/

/GUIDE 115: GASES - FLAMMABLE (INCLUDING REFRIGERATED LIQUIDS)/ Health: Vapors may cause dizziness or asphyxiation without warning. Some may be irritating if inhaled at high concentrations. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite. Fire may produce irritating and/or toxic gases. /Methane; Methane, compressed; Methane, refrigerated liquid (cryogenic liquid)/

/GUIDE 115: GASES - FLAMMABLE (INCLUDING REFRIGERATED LIQUIDS)/ Public Safety: CALL Emergency Response Telephone Number ... As an immediate precautionary measure, isolate spill or leak area for at least 100 meters (330 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Many gases are heavier than air and will spread along ground and collect in low or confined areas (sewers, basements, tanks). Keep out of low areas. /Methane; Methane, compressed; Methane, refrigerated liquid (cryogenic liquid)/

/GUIDE 115: GASES - FLAMMABLE (INCLUDING REFRIGERATED LIQUIDS)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing will only provide limited protection. Always wear thermal protective clothing when handling refrigerated/cryogenic liquids. /Methane; Methane, compressed; Methane, refrigerated liquid (cryogenic liquid)/

For more DOT Emergency Guidelines (Complete) data for METHANE (8 total), please visit the HSDB record page.

UN 1971; Methane compressed

UN 1972; Methane, refrigerated liquid (cryogenic liquid)

IMO 2.1; Methane, refrigerated liquid (cryogenic liquid); methane compressed

49 057 55; Methane

49 057 56; Methane, cryogenic liquid

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.

Flammable Gas

Symbol: F+; R: 12; S: (2)-9-16-33

UN Hazard Class: 2.1